Just a simple thank you and simple Question!

Hey guys, first off I want to thank all you forum members who have helped my SNG play recently. I read this forum frequently and it has just recently made me become a profitable player, and I just want to stop in again and say THANKS for all the support
I deposited $25 onto a site playing strict BR managment playing at the $2 double-up level and have only played double up SNG....In 20 days I have blown through the $2, $5, and $10 levels of these double-ups. Tonight my bankroll hit the requirements for $25 Dubs!!!!
I MUST SAY, it feels great knowing 20 days ago I only had $25 to play with, and now I have a big enough roll to play $25 at once!

Alright, alright.........I'll get to my question so my post doesn't get moved into the bragging section (but really, I'm just showing progress and saying thanks for the support!):
Currently, I have played just over 500 total games [I know, not alot ]. My overall ROI on these double ups is standing at 16%. Everyone says I can only maintain around a 10% overall ROI in these particular SNG. Should I really be moving up to the $25 level with this high of ROI, assuming my ROI will drop to around 10%? I say this because I've only played 500 games and variance is huge......but I guess my question is this: How huge is variance in these double-up tournaments?! I mean, I've never lost more than 5 in a row, but then again my sample isn't very big.
Once again, thanks guys!!!